Known in the art are devices which comprise a main duct and a dead-end channel branching off the main duct wherein a gas bubble is trapped in the dead-end channel when the device is being filled with a liquid fluid. It is also known to integrate a gas-permeable membrane (e.g. PTFE) at the open end of the dead-end channel to allow for a partially or entirely filled dead-end channel. These devices can e.g. be used as actuators using the temperature-dependent extension of the gas bubble to start or stop certain activities of a system. Other uses in the range of micro-fluidics are known. However, the installation of such devices into insulin pumps is not known in the art.
Such a simple dead-end channel structure has big disadvantages if used as a pressure sensor in a liquid fluid-path as the gas bubble inside the dead-end channel can leak from the dead-end channel and invade the main duct. This could lead to a failure in the liquid fluid stream through the main duct such as influencing the amount of liquid fluid reaching the end or outlet of the main duct.